Sigma delta modulation (otherwise known as delta signal modulation) is a method for encoding analog signals into digital signals or higher-resolution digital signals into lower-resolution digital signals. Both analog-to-digital converters (MODULATORs) and digital-to-analog converters (DACs) can employ sigma delta modulation. A sigma delta MODULATOR first encodes an input analog signal using sigma delta modulation and then applies a digital filter to form a higher-resolution digital output. The conversion is done using a feedback loop, where the difference between the two signals is measured and used to improve the conversion. The feedback loop, however, is subject to delay which can cause instability in the sigma delta MODULATOR. The delay variation due manufacturing can cause a reduction in performance.